To determine the chest x-ray findings attributable to normal aging, we evaluated standard postero-anterior chest x-rays taken at least 10 years apart in 67 healthy men initially ages 23-76 years. The mean aortia knob diameter increased from 3.4 plus or minus 0.6 cm. to 3.8 plus or minus 0.5 cm., and mean cardiothoracic ratio (CTR) increased from .41 plus or minus .04 to .43 plus or minus .04. Pulmonary abnormalities on initial chest x-ray consisted mainly of hyperinflation (27 percent) and increased markings (19 percent), both of which doubled in prevalence during follow-up. Chronic obstructive lung disease was suggested in 15 percent of the initial films and 21 percent of the final films despite the absence of clinical or spirometric abnormalities. To define the prevalence of coronary artery disease (CAD), both overt and latent, in a free-living population, we have performed exercise thallium scintigraphy in collaboration with the Johns Hopkins University, Division of Cardiology in approximately 450 individuals from the BLSA. Preliminary analysis of these data has shown an age-related increase in the prevalence of both overt and latent CAD. We have also found that the incidence of subsequent coronary events (angina, myocardial infarction or cardiac death) in asymptomatic subjects is strikingly high in the subset whose thallium scan and exercise ECG are both abnormal. We have also used thallium scintigraphy and exercise ECGs to define a group of men and women ostensibly free from CAD in whom left ventricular function has been measured during maximal bicycle exercise by radionuclide angiography (MUGA), also in conjunction with Johns Hopkins. In these carefully selected subjects, maximal cardiac output did not decline with age--contrary to the body of literature in less intensively screened individuals. Nevertheless, the methods of achieving maximal cardiac output were found to differ with age, the young attaining a more rapid heart rate and more complete systolic emptying, whereas the elderly dependent more upon the Frank-Starling mechanism, i.e. dilatation of the heart during the filling period.